400 Degrees is a common temp to draw back heat treated tool steel to reduce brittleness, increase toughness, and reduce some stress. This temp varies with the type of tool steel being used and the use of the tool. Just as important as the temp being used is the time that the tool is left at that temp. You need to leave the tool in question in the heat range set for a long enough period of time ( depending on material, material thickness, use of tool, etc. ) to have any real impact. I am specifically talking about lower temps, as a higher, more intense heat, i.e., acetlyene torch can have an affect in a very short time. It is doubtful, as already said, that the time and temp needed to bake your finish will have any affect.